Research on the properties of #laminated steel and painted steel in metal packaging applications

The morphology of laminatedsteel and painted steel after the corrosion resistance test is shown in Figure. The corrosion resistance of laminated steel is better than that of painted steel. It is because the PET film on the surface of the laminated steel has the ability to block corrosive substances close to complete blocking, and it is difficult to cause electrochemical corrosion. When the coating is cured on the surface of the metal substrate, tiny pores may be formed. Under the condition of electrochemical acceleration, Can form tiny galvanic cells and accelerate corrosion.

Empty can test

The laminated steel cans and paintedsteel cans were tested with reference to the relevant items in the GB/T 17590-20XX standard. The test results showed that the acid resistance and the integrity of the inner coating film of the two metal cans were all qualified. After the acid resistance test, the inside of the tank There is no phenomenon of peeling, peeling and obvious corrosion on the wall, and the current value of the coating film in the two kinds of tanks is less than 0.5m, indicating that there are no local defects such as scratches and steel leakage on the inner wall of the tank.

The anti-sulfur test shows that there is slight corrosion on the inner wall of the painted steel cans, and the laminated steel cans are better than the painted steel cans. In the retort test, there is a little peeling at the steel flange of the film, which is related to the nature of the film itself. The film as a whole is attached to the surface of the substrate, and the flushing and trimming process will form a certain stress on the flange. Empty cans will peel off after cooking. Baking and annealing the cans before trimming will reduce the residual stress and improve the cooking resistance of the cans. The corrosion resistance test results of laminated steel cans and painted steel cans show that no corrosion spots are found on the inner wall of the laminated steel cans, which belongs to level 0. The corrosion inside the laminated steel cans is severe, belonging to level 3. The corrosion is mostly concentrated at the expansion ring at the bottom, which is Due to the excellent processing performance of laminated steel, deep drawing resistance, wear resistance, and not easy to be damaged during processing, and the lack of toughness of laminated steel, in the stamping process, the coating is easy to tear and produce fine defects. In the accelerated corrosion test of corrosion resistance, The electrochemical impedance of laminated steel and painted steel empty cans will cause corrosion. Both metal cans show a capacitive arc. The larger the radius of the capacitive arc, the greater the polarization resistance, and the better the corrosion resistance. The electrochemical impedance values of laminated steel cans are greater than those of painted steel cans, indicating that laminated steel still has excellent barrier properties to corrosive media and stable corrosion resistance after canning.

Epilogue

(1) The test results of color printing steel show that the acid resistance, sulfur resistance, cooking resistance and impact resistance of laminated steel are equivalent to that of painted steel, while the corrosion resistance and scratch resistance are better than that of painted steel.

(2) The test results of the empty cans show that both the laminated steel cans and the painted steel cans are qualified in the acid resistance and inner coating film integrity tests, and the sulfur resistance and corrosion resistance of the laminated steel cans are better than that of the painted steel cans in the retort resistance test Among them, there is a little peeling at the flange of the laminated steel can, which can be improved by improving the production process

(3) The electrochemical impedance test of empty cans shows that the electrochemical impedance of laminated steel cans is much higher than that of painted steel cans, and the corrosion resistance of laminated steel cans is better than that of painted steel cans.